Method for making and distributing snow



April 27, 1954 w. M. PIERCE, JR

METHOD FOR MAKING AND DISTRIBUTING SNOW Filed Dec. 14, 19m

5 Sheets-Sheet l l INVENTolL MYNE MPIEREE, JR.

AT TRNEY April 27, 1954 w. M. PIERCE, JR 2,676,471

METHOD FOR MAKING AND DISTRIBUTING SNOW Filed DSG. 14. 1950 I5V Sheets-Sheet 2 l l 5 62 gli 495.95553 43 -jlg 4# INVENTOR. MYNE MPIERUE, JR.

AT'TORNEY April 2,7,- 1954 W. M. PIERCE, JR

METHOD FOR MAKING AND DISTRIBUTING SNOW Filed Dec. 14. 1950 3 Sheets-Sheet 5 INVENTOR. y VVYNE l/LPJEREE, JR.

MMX

Patented Apr. 27, 1954 UNITED STATES PATENT OFFICE METHOD FOR MAKING AND DISTRIBUTING SNOW Wayne M. Pierce, Jr., Milford, Conn., assignor to Tey Manufacturing Corporation,

Milford,

6 Claims.

This invention relates to a new and useful method of making snow and to an installation for the economical manufacture and application of snow as a covering or coating for ski trails or the like in such quantities as to be useful for skiing and other winter sports.

In recent years the enormous growth of interest in and the great increase in the number of people participating in winter sports has resulted in the growth or establishment of large-scale business enterprises, the economic welfare of which is subject to the whims of the weather. On such winter sports is dependent a large industrial segment comprising ski area operators, ski lift operators, lodges, and manufacturers of winter sports equipment and the like. In recent years there have been marked variations in snowfall and accumulation in the north eastern portion of the United States and adjacent portions of Canada with the result, for example, that the ski seasons of 1948-1949 and 1949-1950 were extremely poor and occasioned considerable hardship upon those whose livelihood is derived from the winter sports business.

It has therefore become evident that could a means or method or apparatus be developed to economically produce snow upon slopes of ski areas, the financial hazards connected with those in the ski industry would be materially reduced. Heretofore, attempts have been made in the indicated direction. One line of such attempts was to use non-water products such as straw, pine needles and sand on ski slopes. These attempts were somewhat successful, as novelties, but gave very poor simulation of natural snow conditions.

A second line of attack on the problem has been the use `of cracked or chopped ice, preparing it generally by machine from ice blocks and distributing it to the surface of the ski slopes and areas by means of blowers. This approach gave superior results to those obtained by the use of non-Water products but the cost of the raw ice or ice blocks, the slowness of distribution and the fact that the end product is still not snow leaves much to be desired.

On page 308 of Meteorology by Louis B. I-Iarrison, New York National Aero Council Inc. 1942, chapter 17, Glossary of meteorological terms, and reprinted by permission from part VIII of W. B. Circular M prepared by Weather Bureau, U. S. Department of Commerce, snow is defined as follows:

Snom-Precipitation in the form of small ice crystals, falling either separately or in loosely coherent clusters (snowflakes).

Nora-Sometimes a considerable number of snowiiakes and detached, simple ice crystals fall together. In extremely cold weather in high latitudes precipitation may occur exclusively in the form of detached, simple ice crystals.

It is therefore an object of the invention to provide a method and an installation whereby snow may be economically manufactured and distributed over a desired surface or surfaces, such as ski areas or ski trails, in such quantities as to be useful in winter sports.

Another object is to provide an improved nozzle and an improved structure comprising a battery of ski mounted nozzles for use in the making of snow.

Other objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein certain methods of and installations for practising the invention are illustrated. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawings:

Fig. 1 is a perspective View illustrating an installation, according to the present invention, on a ski trail;

Fig. 2 is an enlarged schematic view of the apparatus of Fig. 1;

Fig. 3 is a perspective view of a battery of ski mounted nozzles employed;

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 5;

Fig. 5 is a front elevational view of the nozzle of Fig. 4;

Fig. 6 is a central longitudinal sectional view on a larger scale of an inner part of the nozzle of Figs. 4 and 5;

specific examples are given hereinafter, it is pointed out that in actual experiments I have converted over two tons of water to snow in a matter of eleven hours at a power expenditure of .95 horsepower per ton (per 24 hours) at an average free-air temperature of 25 F.

According to one embodiment of the invention (see Fig. 1) an installation is made along one side of a ski trail I6. This same installation, or similar type of installation, would be made along a ski jump, toboggan run, or for similar areas. In Fig. 1, water from a source II, as a brook, is taken into a pump I2, as through an intake pipe I3, and delivered to an accumulator I4. The water from the accumulator must be under a pressure sufficient to carry up the hill or mountain I on which the ski trail Ill is constructed.

Thus, the accumulator I4 feeds into pipe I6 generally parallel with the ski trail and at one .side thereof and which pipe at suitably spaced intervals is provided with a series of individually valve controlled outlets numbered in the drawings as V51-23. At a point, preferably at its lowest point, pipe or line I6 is provided with a drain cock D whereby such pipe may be drained when not in use to avoid damage through freezing of water in the pipe. The pressure is such that at the uppermost outlet, water is available at a pressure of forty pounds per square inch.

At the same time, air is compressed by a compressor 24 and distributed through a pipe or line 2-5 running substantially parallel with the pipe or line I3. Pipe or line 25, also at suitably spaced intervals, is provided with a series of valve controlled outlets 26, 21, 28, 29, 30, 3I and 32. As shown in the drawings, the valved outlets of the water pipe I6 and air pipe 25 are arranged in pairs in that wherever an outlet is provided in the pipe I6, an outlet is also provided in an adjacent portion of the pipe 25.

To make and spread snow, a pair of the valves in the distributing lines as, for example, valve I8 of line I6 and valve 21 of line 25, have a pair .of flexible hoses 33 and 34, respectively, connected with them. Such hoses are connected respectively with the manifolds 35 and 36 of a device (see more particularly Fig. 3) generally designated 31. Device 31 is a distributing means and is shown as comprising a structure mounted on ground engaging means, such as the runners or skis 38, and including a battery of similar nozzles each designated 39 and all, here shown, as facing in the same general direction. However, the nozzles may face oppositely and/or the end ones may face laterally outwardly if desired and any or all of them may be oscillated or otherwise movably mounted.

Water and air being available in the lines I6 and at the proper pressures and the device 31 being connected with the flexible lines 33 and 34, the operator adjusts the water and air regulating valves of outlets I8 and 21 whereby the desired type of snow will be made. Then the operator shifts the device or structure 31 along a portion of the trail I I) or other area to be covered with snow. It is noted that a device 31 may be connected with each pair of valved outlets, the latter being so spaced and the exible hoses 33 and 34 being of such lengths that the entire trail may be covered with snow. That is, at any one time, a device 31 may be connected with each pair of valved outlets or only certain of the outlets may be in use, as required.

In the apparatus or device 31, the manifolds 35 and 36 are shown as in spaced parallel relation being secured to the ground engaging means, as skis 38, as by clips or brackets 4u and 4I, respectively, to which the respective manifolds may be fastened in any desired manner, as by welding. From the manifold 35 risers 42 are connected toconvey water from the manifold to the inlets 43 of the respective valves 39. Then other risers or pipes 44 serve to connect the interior of manifold 36 with the air inlets 45 of said nozzles. In large installations, or where necessary, structures 31 each comprising a battery of nozzles may be moved by a tractor, truck, "snow cat," etc.

The nozzle 39 comprises a rigid cast body 46 having an inner tubular projection 41 centrally arranged and in the outer end of its side wall 48 being recessed as at 49. The tubular innerprojection 41 is aligned with and communicates with the air inlet and in an inner portion is interiorly screw threaded as at 50. Located in the 'tubular projection 41 is a tubular nipple 5I having external screw threads I52 on its inner end portion for threaded engagement with the threads 5U before mentioned whereby the tubu- -lar nipple 5I is located and secured in position.

Through its inner portion, nipple 5I has a relatively large diameter passage 53, the diameter of which is reduced toward the forward end of the nipple as in a taper 54 communicating with a restricted neck or passage portion 55 opening again into an enlarged diameter portion 56. In this enlarged diameter portion 56 there may be a pair of spaced sockets 51 for engagement by a spanner wrench or similar tool for threading the nipple into and out of place.

Over the open front end of the body 46 there is secured a plate 58 the inner corner portions of which are cut away to receive a compressible rring or packing 59 and this plate is of a diameter to be received in the before mentioned recess .43. Plate I58 has a discharge orice therethrough comprising a straight sided opening portion 69 and a flared opening portion 6I. Portion 6I begins at the forward end or outer end of portion 60 and extends through the front side of the plate 58.

Means being provided for securing the plate 58 in position, the nozzle 39 as thus far described may be used in the making of snow. It comprises an external mixing type of nozzle as the mixing of the air and water takes place in the flared or bevelled orifice portion 6I. However, this nozzle, in use, produces a weird penetrating noise audible for great distances and annoying to the operators and to those at considerable distances away.

To overcome this objection, Without loss of eiiiciency, I mount a member 62 on the front or discharge end of nozzle 39. Said member includes an annular wall 63, the inner end of which overlies the edge of plate 58. Then screws 64 passing through wall 63 are threaded into the front end of nozzle body 46 securing member 62 in place and through the latter securing the plate 58 in place. Member 62 also includes a front wall 65 having a great many small nozzles 66 or ,openings in the form of nozzles therethrough. Openings or nozzles 66 each include an inner tapered portion B1 and a straight sided outer or discharge portion 58 and are all arranged radially outwardly of an enlargement 69 on vthe inner surface of front wall 65.

In the use of this nozzle 39, without the front member 62, water under pressure entering through the inlet 43 entirely surrounds the tubular projection 41 and is against the inner surface of the closure plate 58 of the nozzle. The forward end of the tubular nipple 5i is located adjacent the inner surface of the central portion of said closure plate and so the water moves radially inwardly in a plane normal to the axis of the discharge oriiice through plate 55. That is, the water so moves between the said closure plate and the front end of the tubular nipple as to form a relativelyY thin film, as into the space S (Fig. 4). Due to the enlargement 56 of the discharge through the nozzle 5l this Water is exposed across a, good portion of the discharge end. of the nipple.

Air under pressure is being supplied through portions E2 and 63 through the center of the plate 58. Thus, the blast of air from the nipple is, in effect, against the center portion oi a thin sheet or" water and the air and water are projected out through the discharge orifice comprising the portions 52 and B3 at high velocity in the form of a mist or fog in which the water is broken down into minute particles. As the mixing takes place in the orifice portion S3 this is an external mixing type of nozzle.

The thickness of the mentioned sheet of water and thus the proportion of water to air may be controlled by the threading of the tubular nipple 5I more or less into the tubular projection 41 whereby to have the front end of such tubular nipple closer to or further from the inner surface of the closure plate 58. Any such adjustment controls the thickness of the space S through which the above described thin sheet of water moves to be engaged by the blast of air from the nipple 5I.

With the member S2 added, nozzle 39 is of the internal mixing type. Actually, the unit becomes a two-stage internal mixing nozzle. That is, mixing occurs, as first described above, by the air and water moving through oriiice portions 88 and 6|. This now produces a coarse vapor which is deiiected laterally or radially by the enlargement 69 and is slowed in its movements and thus its pressure increased. Now it is re-expanded as it moves out through the multiple of small ports or nozzles 65 in the form of a fine vapor or mist moving at high velocity and which will become snow.

The two-stage nozzle is of advantage since in moving through the orifice t-EI the air is at its coldest. However, at this time, some particles oi water may move through the orifice without actually being contacted by the air. In such instances, the particles of water are violently tumbled about and a great turbulence established. Then the water particles are thrown violently into contact with one another and serve to batter and break one another into ne particles creating a fine mist.

With member 52 in place, the action through oriiice Sil-S! is slow and a coarse mist will result. Such coarse mist is deflected laterally or radially of the enlargement 69 and the water particles in the mist may regroup and all particles of water are contacted by the air. Then as this mixture or mist moves out through the many small nozzles E6 in the face of member 62 there is a forced intermingling or intermixing of the air and water particles, cooling the latter to the limit of the air employed and thus taking ad- 6 vantage of all the cooling capacity of the expanding a-ir.

From the foregoing description it will be seen that the basic necessities for the practising of lthe invention consists of a supply of water, a

source of compressed air, a mixing nozzle and coupling means for connecting the water and air to the nozzle together with control valves for regulating the air-water ratio depending on atmospheric conditions and the type of snow desired. The actual nozzle design is subject to wide variations, i. e., it may be round, nat, or the like and* may vary in design and/or structure.

For example, in Fig. 7, the air passage of the nozzle 16 as designed has a converging orifice to expand the air thus cooling it and increasing its velocity. In this figure, the air inlet to the nozzle is designated 1 I While the water inlet is designated 'l2 and the latter is connected to carry water as from a supply 13. In the structure schematically suggested in this figure, the high velocity cold air stream is projected into the water stream to atomize the water and disperse it throughout the atmosphere on a directed course. It water pressure is available the syphoning action of Fig. '7 is not necessary. Clearly, in that iig-ure, the nozzle design is such as to employ the compressed air moving into the nozzle from the supply line 1I as an ejector to draw the water from the source 13 into and through the nozzle and into the air stream.

Another example of the type of nozzle which may be employed is illustrated in Fig. 8. In this ligure, the nozzle is generally designated 74 and water is supplied the nozzle under pressure as through an inlet 'I5 while air is supplied under pressure through the inlet 76. The water and air are thus mixed under pressure relatively close to the nozzle exit and then the mixture expanded through a converging nozzle 14.

While the nozzle 39 is very much preferred and is the most practical and efficient of those disclosed, and represents a substantial advance over the art, all of these nozzles are disclosed herein generally for the purpose of showing nozzles which may be used. Thus, the nozzles 'l0 and 14 of Figs. 7 and 8 might be substituted for the nozzles 39 of Figs. 1-6. This nozzle 39 has also been found of great advantage in the making of a fog for the ghting and extinguishing of cer tain types of res.

For smaller installations than suggested in Fig. 1, the apparatus for laying down the snow could be self-contained consisting, for example, of the ambulatory unit of Fig. 9. Such unit ccnsists of a port-able carrier l1 including ground engaging means, shown as wheels, having mounted thereon a water tank I8 together with a pump 19 and an air compressor 88, all driven in the desired manner. In this equipment, the compressor 8B is connected with a reservoir 81 from which a lead 82 extends to a manifold 83 corre spending with the manifold 35 first described.

Then the pump I9 takes Water from the interior of the tank 18 through a pipe 84 and pumps such water through a pipe delivering the water to a manifold 8E corresponding with the manifold 35 of the battery structure 37 above described. From the manifolds 83 and 86 there are permanent connections to a battery of nozzles 39a, each connection being equipped with a valve 8l for manual and individual adjustment. Nozzles 39a of Fig. 9 are the nozzles 39 previously described. Thus, in each of Figs. 3 and 9, I have a battery of mixing nozzles movable as a unit on ground engaging members whether skis, runners or wheels, etc.

With this equipment, snow would be made and distributed through the nozzles 39a fixed as shown in Fig. 9, or these nozzles might be connected with their respective manifolds by means of flexible hoses, where that is desired. Additionally, while the nozzles 3M are shown as iixedly mounted and all extending in the same general direction it will be understood that, if desired, the nozzles may be mounted for oscillating or other movements and may extend or face as desired.

With the portable device of Fig. 9, pressure on the water may be established in ways other than above suggested. Thus, a head of air under pressure may be maintained on the Water in tank 18. Additionally, where syphoning types of nozzles are employed they will serve to eject or draw the water from the tank.

This portable type of equipment is to be driven to the area or along the trail, etc. which is to be coated and may be used for coating such area or trail, etc. and for building up the quantity of snow thereon or for the building up or patching up of worn areas, etc. In connection with this matter of building up or patching up of Worn areas, any of the various valved outlets of Figs. l and 2 may be tapped for the purpose of making snow adjacent such outlets to patch or build up any section or portion of a ski trail or the like which has become worn or thin.

All of the illustrated types of nozzles have been tried and water pressures from to 100 lbs. per square inch gage and air pressures from 0 to 200 lbs. per square inch gage have been used. For example, at an ambient temperature of 31 F. and less, snow has been made at any air pressure from to 209 lbs. per square inch by varying the water pressure to give a snow making mixture. The most economical runs (highest quantity of water handled per horsepower used) have been made at temperatures below 28 F. and with a water pressure of 50 lbs. per square inch and an air pressure of 45 lbs. per square inch. Snow has actually been formed at a temperature as low as 0 F.

It is noted that it is not practical to make nozzle 'llt (Fig. 8) of a size or capacity to equal that obtainable with nozzle 39. When a nozzle of the type of 'Hi is greatly enlarged the water is not all atomized. Large drops or globs of water pass from the nozzle in a fixed pattern.

In operation, the nozzles are directed over the area to be covered with snow and when the ambient temperature is 32 F. or less and adjustment is made for the proper proportions of waterto air, snow will be made to form in the atmosphere and precipitate onto the ground. The adjustment is made by varying the water or air pressure or both. Any adjustment made is occasioned by the necessity for obtaining a proportion of water and air, depending upon the ambient temperature and the humidity.

The exact manner in which the snow is produced is not known. However, a reasonable theory is believed to be that under proper conditions of adjustment, the cooling effect of the air stream is sufficient to convert a small portion of the water particles, not exceeding .010 inch in diameter, into ice crystals to act as seeding agents.

At the same time, the remainder of the water particles are intermixed with the free air to be super-cooled by said air. In this way, a cloud is formed of the mixture being projected by the nozzle and various particles (ice crystals and super-cooled water particles) contained in the cloud intermix due to the motion imparted by the velocity of the expanding air. This intermixing due to relative motion of the particles results in the super-cooled water particles sublimating onto the ice particles because of their differential pressure thereby forming larger particles which precipitate as snow.

Some of the super-cooled water may contact the ground or other surface or previously formed snow and sublimate out as soft rime. If the proportion of water to air is such that the free air may not super-cool all of the water particles, such particles will precipitate or fall as water and if they fall against surfaces below 32 F. will form a glaze thereon.

On the other hand, if the proportion of water is too small, all the water projected from the nozzle may be formed into very fine ice or snow crystals constituting an ice fog. The particles of such ice fog are so fine that they precipitate only very slightly or not at all and tend to float with the wind and thus may pass over and not precipitate onto the surface which it is desired to cover or coat.

By adjustment of the ratios of water-toair, the consistency of the manufactured snow can be regulated from a dry, powdery snow through a wet, heavy snow down to an ice glaze. This variability of consistency is of great advantage, since, for example, a slope may first be covered with an ice glaze and then this ice glaze may be covered with a heavy, wet snow and then the heavy, wet snow covered with a dry, powdery snow providing the surface. In this way, a hard, durable base is provided to prevent fast wearaway by the skiers and yet an ideal surface is available.

With the lowering of temperature and the increase in humidity of the free air, the efficiency of the present method increases. That is, the practice of the method will result in the conversion of more water to snow per unit of compressed air consumed. Actually, experiments indicate that under certain atmospheric conditions, the present method may be used to seed the atmosphere and thus induce natural precipitation.

The efficiency of the nozzle in mixing pounds of air and pounds of water, of course, determines the ultimate efficiency in the practising of the method. rEhe mixture is projected from the nozzle partially in the form of ice particles but for the most part in the form of particles of water and at very high velocities. A velocity of Mach #l (representing an air pressure differential across the nozzle of at least two atmospheres) or more appears to be the ideal in practising the present method.

In the spray or mixture projected from the nozzle as hereinbefore described are the tiny 1ce crystals of relative negative vapor pressure and adjacent super-cooled water particles of relative positive vapor pressure. These particles are drawn to and coat the ice crystals building up the sizes of the latter so that they tend to fall. In falling, or precipitating, they collide with other water particles and thus collect the latter and themselves continue to increase in size by this building up process.

As these super-cooled water particles are converted to the solid state they release heat to the air, which released heat tends to cause the air to rise and so additional air is drawn in behind g, the rising air or below it thus setting up a turbulence to continue the intermixing of the projected particles resulting in a chain reaction and the building up of the ice crystals into snow crystals, which precipitate, and the constant drawing into the turbulent mass of fresh cold Where the snow is to be used in packing vegetables, the spray will be directed into a closed chamber having therein a temperature of notl more than 32 F. Also, instead of distributing the snow as it is produced, i. e.J producing it on the ski trail or the like, it may be made in a pile and then distributed. When making snow in a closed chamber, if the ambient temperature is high, the air is rst cooled. This may be accomplished by any desired means as, for example, the employment of the Joule cycle.

In this specification and in the accompanying claims I have described the products of my method as snow. Actually, thisI product under microscopic examination answers the above quoted definition of snow. rThe following are specific examples of practice of the invention:

Example I Nozzle of the type of Fig. l impinging air stream on water. Water line pressure 4G lbs. per square inch and air line pressure 125 lbs. per square inch. The run continued for approxtmately 16 hours from 5: 38 p. m. until 9: 28 a. m. of the next day with the ambient temperature Varying from 20 F. through 15 F. to 27 F. Temperature of lair at the compressor intake varied from 62 F. down to 45 F. At the beginning of the run the nozzle was adjusted until snow was formed and snow was formed at all the temperatures mentioned.

Example Il Nozzle employed was of the internal mixing type with an opening 1/2" x .832". The run was four hours from 6: 00 p. 1n. until 10:00 p. m. The temperature of the water was 51 li'. and of the air at the compressor intake 55 F. During the run, 25.65 cubic feet of water was used and the ambient temperature was approximately 16 F. Water pressure of e() lbs. and an air pressure of 40 lbs. per square inch was used and a damp snow was produced.

Example III The nozzle was of the internal mixing type having an opening .050" by 1/2" and the run was for seven hours from 00 p. m. to 3: G0 a. with a water temperature of 43 F. 29.2 cubic feet of water was used and the snow produced ranged from damp at high temperature to a dry at low temperature. The water pressure was 33 to 43 lbs. per square inch with the air pressure at 33 to 43 lbs. per square inch and at a temperature or 55 F. at the compressor intake. During the run, the ambient temperature varied from F. to 12 F. to 15 F.

Example IV Nozzle employed was the external mix type with two impinging air streams on the water stream (Fig. l). The run was for ll hours. At the compressor intake the air temperature was 55 F. 71.6 cubic feet of water was used or convetted to snow. Pressure of the water employed was lbs. per square inch and the a1r pressure was 40 to 50 lbs. per square inch. The ambient temperature varied from 28 F. to 20 l()y to 27 F. and the manufactured snow was from. medium to light.

Having thus set forth the nature of my invention, what I claim is:

l. 'Ihe method of making snow in flake form at a ski trail location and depositing the flakes as formed upon the trai1 surface in order to provide the trail with an optimum snow cover for skiing, which method comprises injecting into an ambient atmosphere at said location, having a temperature of not more than 32 F. and not less than 6 F., a mist or fog formed from water and propelling and cooling the particles of water in said mist by the projection of rapidly expanded air supplied from a compressed air source so as to form snow flakes in the atmosphere over the trail which snow flakes precipitate directly upon the trail surface.

2. The method of making snow in flake form at a ski trailrlocation and depositing the flakes as formed upon the trail surface in order to provide the trail with an optimum snow cover for skiing, which method comprises injecting into an ambient atmosphere at said location, having a temperature of not more than 32 F. and not less than 0 F., a mist or fog formed from water and propelling and cooling the particles of Water in said mist by the projection of rapidly expanded air supplied from a compressed air source so as to form snow flakes in the atmosphere over the trail which snow flakes precipitate directly upon the trail surface, the snow initially produced having a relatively high water content to produce a wet snow freezing on the trail and forming a hard base layer, and at a later stage. increasing the proportion of air to Water to form a top layer or relatively dry snow.

3. The method of making and distributing snow on a ski trail comprising atomizing a quantity or water to form myriad Water particles, and projecting the water particles at high velocity by rapidly expanded compressed air into an unobstructed ambient atmosphere above the ski trail which atmosphere has a temperature of not more than 32 F. and not less than 0 F., whereby the Water particles are cooled by the expanded air and whereby the Water particles are converted to snow as they progress into the atmosphere and precipitate on the ski trail in such quantity as to be useful for skiing.

4. The method of making and distributing snow on a ski trail which comprises atomizing a quantity of Water by air to form myriad water particles some of which do not exceed .010 inch in diameter, the quantity of water being supplied from a source of water under a pressure of between l0 and 6G pounds per square inch, and the air being supplied from a source of air under a pressure of between 30 and 200 pounds per square inch, projecting the Water particles by rapidly expanded compressed air from said compressed air source into an unobstructed ambient atmosphere above the ski trail, which atmosphere has a temperature of not more than 32 F. and not less than 0 F., such projection having a high velocity, whereby the Water particles are cooled by the rapidly expanded air and whereby the water particles are converted to snow as they progress through the atmosphere and. precipitate on the ski trail, and shifting the location or' said projection of particles with respect to the ski trail to build up a substantially uniform layer of snow on the trail.

5. The step in the method of making and dis- E u tributing snow on a ski trail which comprises impinging a stream of water on a jet of rapidly expanded compressed air in an unobstructed ambient atmosphere above the ski trail which atmosphere has a temperature of not more than 32 F. and not less than 0 F., said jet having a velocity of approximately Mach #1, whereby the Water is caused to form myriad Water particles some of which do not exceed .010 inch in diameter, and whereby the water particles are cooled by the rapidly expanded air, and progressing the water particles through the atmosphere so that they are converted to snow and precipitate on the ski trail in such quantity as to be useful for skiing.

6. The method of making snow which method comprises atomizing a quantity of water by air to form'myriad water particles some of which do not exceed .010 inch in diameter, the quantity o1 Water being supplied from a source of water under a pressure of between 10 and 60 pounds per square inch, and the air being supplied from a source of air under a pressure of between 30 and 200 pounds per square inch, and projecting the water particles by rapidly expanded compressed air from said compressed air source into an unobstructed ambient atmosphere above a snow'- receiving surface, which atmosphere has a temperature of not more than 32 F. and not less than 0 F., such projection having a high veiocity, whereby the Water particles are cooled by the rapidly expanded air, and whereby the Water particles are converted to snow as they progress through the atmosphere and precipitate on the snow-receiving surface.

References Cited in the iile of this patent UNITED STATES PATENTS 

